This invention relates to a method of mounting fuse holding clips for a fuse holder on a circuit board and more particularly an improvement on a method of mounting fuse holding clips by an automatic part inserter after they are cut away from a lead frame including a plurality of fuse holding clips having mounting legs to extend through mounting holes in the circuit board and to be securely mounted on the circuit board by a soldering layer.
In general, there has been used an autoamtic part inserting machine which mechanically and continuously inserts a plurality of fuse holding clips at their mounting legs in mounting holes in a circuit board.
There has been also used an assembly of fuse holding clips to be mounted on the circuit board by such an automatic part inserting machine. Such an assembly of fuse holding clips may be referred to as taped clips and comprises a lead frame having a perforation engaging feeding pawls of a sprocket of the automatic part inserter with the fuse holding clips at their mounting legs integrally provided with the lead frame in a spaced manner.
As shown in FIGS. 12 and 13, each of the fuse holding clips 12 comprises a resiliently fuse holding clip body 18 including mounting legs 22 integrally provided therewith. The clip body 18 comprises a generally U-shaped curved piece 20 for resiliently holding one of bases of a fuse such as a cartridge fuse and an upper base receiving opening 24 provided at the end of the curved piece 20 and widened toward its upper edges as shown in FIGS. 12 and 13.
The automatic part inserting machine feeds the taped clips to a clip mounting position by rotation of its sprocket and removes the respective fuse holding clips at their mounting legs out of the taped clips by holding them by means of a chuck of the machine and cutting them by means of a cutter thereof.
Thereafter, the machine pushes down the respective fuse holding clips by a pusher 42 of the machine which engages the generally U-shaped curved piece 20 of the resiliently fuse holding clip 12 at its inner bottom while inserting the mounting legs 22 of the fuse holding clips 12 into the mounting holes in the circuit board until an outer bottom 20b of the U-shaped curved piece 20 engages the upper face of the circuit board.
Finally, the mounting legs of the fuse holding clip are clinched by a clincher of the machine so that they are bent along an underside side of the circuit board toward an electrically conducting layer thereon and soldered thereto so that they are electrically and mechanically connected to the electrically conducting layer.
In a conventional manner, the automatic part inserter for inserting a large-sized radial parts into a circuit board has been also used for inserting the fuse holding clips 12 into the circuit board. Thus, the automatic part inserting machine comprises the pusher 42 having a lower dead point set at 5 to 20 mm distant from an upper face of the circuit board where such large-sized radial parts are most suitably inserted into the circuit board.
However, such a lower dead point of the pusher 42 is too high for the fuse holding clips 12 to be inserted into the circuit board because the pusher 42 of the automatic part inserter engaging the inner bottom 20a of the U-shaped curved piece 20 of the fuse holding clip 12 cannot be lowered until the outer bottom 20b of the U-shaped curved piece 20 reaches the upper face of the circuit board as shown in FIG. 12.
Thus, it is required that the fuse holding clips are so designed that the pusher 42 of the inserter can engage the fuse holding clips at their position as high as possible. For example, it is required that the upper edges 24a defining the upper base receiving opening 24 of the fuse holding clip 12 for receiving the base of the fuse is so narrowly spaced that, the pusher 42 of the inserter can engage the edges 24a of the upper base receiving opening 24 as shwon in FIG. 13.
However, the fuse holding clips 12 having the thus narrowed upper base receiving opening 24 as shwon in FIG. 13 are not suitable for receiving such fuses as having bases of relatively larger outer diameter. Furthermore, the fuse having the bases of relatively larger outer diameter should be inserted through the narrowed upper receiving opening 24 of the fuse holding clip 12 by a relatively higher inserting force, which causes the fuse to be disadvantageously damaged.